The present invention relates to a curtain airbag device that promptly covers a window portion of a vehicle, such as an automotive vehicle, train, ship, aircraft, or space vehicle, or a structure, such as a house, building, or space station.
A curtain airbag device, in which a curtain-shaped airbag is accommodated at a periphery of a window portion of a vehicle and the airbag is inflated by gas that is supplied at a vehicle crash or a rollover so as to cover the window portion promptly, is generally known. In this device, a passenger could not be protected properly by the curtain airbag device unless a proper tension is provided at the curtain. For example, in a case where the curtain is folded and accommodated at a portion along one window side and both window sides next to this window side of a rectangular window portion, the curtain may be inflated with its tip portion having a total length of these three window sides. Namely, the length of the free tip portion of the curtain inflated becomes relatively long, so the curtain tends to be turned up even with a relatively small force applied. As a result, the protection of the passenger could not be properly attained.
In view of the above problem, there are generally provided a plurality of inflatable portions (bags) that extend from one window side of the window portion toward the tip portion of the curtain so that an entire width of the curtain in an inflated state can be reduced by these inflatable portions, namely the length of the free tip portion of the curtain can be shorter, thereby providing a large tension at the curtain. However, it may be difficult to obtain a sufficiently large enough tension. Further, since considerably large inflatable portions may be required to cover a large window portion, a large-sized inflator may be also necessary to supply a large amount of gas to the large inflatable portions. Thereby, application of the curtain airbag device to the large window portion would be difficult.
US Patent Application Publication No. 2004/0066022 A1 discloses a curtain airbag device for a vehicle back window, in which a curtain portion is placed in the folded state at an upper peripheral portion of the back window and tension-providing support points are provided respectively at middle portions of the both-side peripheral portions of the back window, wherein the curtain portion is inflated downward from the tension-providing support points, thereby generating the tension with the tension-providing support points.
The above-described patent publication also discloses another curtain airbag device, in which there are provided guide rails extending vertically at the both-end portions of the back window, wherein the curtain portion placed at the upper peripheral portion is moved down along the guide rails, thereby lowering a tension line by moving the tension-providing support points downward.
However, in a case where the tension line is lowered by moving down the tension-providing support points as described above, a distance between both tension-providing portions by way of the upper peripheral portion of the window portion becomes relatively long. Namely, the length of the curtain located between the tension-providing portions (the width of the curtain) in the inflated state becomes considerably long, and therefore a large amount of gas supply would be required to inflate the large inflatable portions for generating a desirable tension properly.
Further, since the tension-providing portions move as described above, the guide rails would generate a sliding resistance for the inflation of the curtain. Thereby, a smooth and prompt inflation of the curtain could not be attained properly.